In U.S. Pat. No. 3,215,409, a mixer is disclosed which provides rapid and intense mixing action. This mixer differs from the mixer of the instant invention in both structure and mixing action. The mixer of the instant invention has: (1) no blades exterior to the disc pair; (2) a second blade perpendicular to the radially extending blade; (3) in the preferred embodiment, all blades are connected to both discs to form compartments; and (4) slots in each disc are positioned between the blades pairs and, in said preferred embodiment, of an optimum size. The second blade and optimum slot size are necessary to generate the high value of turbulent intensity accomplished by the instant invention. This structure, of course, fixes the mixing action.